As an important component of a mobile communications network, a base station antenna is responsible for the functions of transmitting and receiving electromagnetic waves. The performance of the mobile communications network is directly affected by the performance of the base station antenna, and a downtilt is an important contributor to the performance of the base station antenna.
In an active base station antenna system, two or more TRXs (Transceiver) and a vector synthesis feed network feed power to multiple antenna units to produce a radiation beam with a downtilt angle. The inventor finds that when the number of TRXs is relatively small, for example, there are only two TRXs, an adjustable range of a downtilt of the base station antenna is relatively narrow, making it difficult to meet actual requirements of a communications system.